Blog for the RepRap project at www.reprap.org - a project to create an open-source self-copying 3D printer. To get all the early posts on this blog with all the images as a single PDF visit this page.

Wednesday, February 03, 2010

Mini Me

Just before he left to Starve in the New Zealand Wilderness Ed did a new RepRap design because he "had to get it out of his head". It was a mini version of Mendel. You can see it on the left in the picture above - a still fromJosef Davies-Coates' short documentary on the Bath RepRap Lab. The machine uses M6 threaded rods and M3 nuts and bolts (as opposed to the M8/M4 used on Mendel) and NEMA 14 steppers. The reprapped parts are about 30% of the volume of those for Mendel, which is to say it could reproduce three times faster.

This is a completely unsupported design for the moment (we haven't got the time...) but we have put the STEP file for it in the RepRap repository at

I opened up the STEP and took some screen shots. It looks good: http://picasaweb.google.com/M.BrittCrane/MiniMendel#5434059538017842002http://picasaweb.google.com/M.BrittCrane/MiniMendel#5434059550831420722

Mini Mendel would be great for people who don't mind a smaller build size, (~110x140x?). It really would be easier to reproduce than the full sized Mendel. Not only is the total RepRapped parts volume 1/3 that of Mendel, the larger more difficult parts are much smaller and thus easier to print, particularly with ABS. However, I suspect the cost would only be marginally smaller.

I'm wondering, would it be less or more stable at when the X-axis makes rapid moves at a high Z-level? Since the Darwin has diagonal ties in all directions, and the Mendel only has triangle frames to make the frame itself stiff. There is no movement that requires the stiffness because the platform moves in this direction, not the printhead, so this is just for robustness of the machine, it seems?

Of course this can easily be tested experimentally: If you print a really tall rod in the machine (e.g. a 10cm piece of makerbeam), it be wider at the base and smaller at the top.

At 1/3 of the build time, this really reduces one of the limiting factors in getting a new Reprap out the door. Given its improved ability to self-replicate, I'd argue that this is more "Reprap" than the full Mendel, and deserves full support!

If people get a MiniMendel and want/need a bigger one, they can print their own parts for a full-size Mendel and even give the mini-frame to the next needy soul! "Village Bike" Reprapping!

Someone wants me to make them Mendel parts. I'm gonna offer Mini-Mendel instead if it gets proper build documentation somewhere and the files get STL'd soon. I'll print one for myself too, and it'll still have only taken 2/3 of the time I'd have had to devote to a full Mendel, and there'll be two new printers in the world.

Here is a simplified design of mini Mendel:http://picasaweb.google.com/M.BrittCrane/MiniMendel#5434173952181178850http://picasaweb.google.com/M.BrittCrane/MiniMendel#5434173802249755506http://picasaweb.google.com/M.BrittCrane/MiniMendel#5434173807787881330

I went for Building one 1/2 size its strange its almost addictive when you have a vision of what a build is going to look like you cant stop I know exactly how Ed felt.I figured 1/2 size was enough to do 100x100x70 builds tho.I guess I must of calculated it wrong

Sorry I should clarify, I put the same ones up, just so everything is in the same place for clarity. If anyone finds any errors, I can get originals out of Solid Edge, if you let me know I'll update as needed.

One other thing that hasn't been mentioned. The mini-mendel hasn't been fully tested. It's just been put together without the extruder and we've all stood back and said something like "awww look how cute it is!", but that being said all the axis seem to run quite nicely.

So it's still to print its first part. I don't think this is going to happen in Bath anytime soon, so the race is on amongst the community so to speak. Oh and thanks to RustySpoon at thingiverse for the STL conversions.

MakerBot can print all the reprapped parts for a standard Mendel (we deliberately made Mendel that way), so - if it can print at all :-) - Mini Mendel will definitely be able to make a full Mendel as it has a bigger print volume than MakerBot.

If you are making improvements or anything to do with the Mini-Mendel it would be greatly appreciated if you posted or linked-to your work from that page so that it's easily accessible in the future (it's a wiki; you can edit it!).

Hi there,I am a newbie to RepRap, and am very excited about the whole concept.I want to start by building a Mendle, but all the parts I have come across are .stl which I cant open. Is there any way for me to get .igs or .step or preferably Inventor, because that is the program I work in?Tony

Hi there,I am a newbie to RepRap and am very excited to get going . I want to build a Huxley, and have got very frustrated trying to download any plans that can be opened. Could anybody point me in the right dirrection please? I do all of my work in Inventor so any file types such as .igs or .step would work. I dont know why it seems so complicated!ThanksTony